Scientists from Northwestern University have boosted adults' memory by using Transcranial Magnetic Stimulation (TMS) - a non-invasive process that involves zapping a patient’s head with an electrical current using magnetic pulses in order to stimulate specific regions in the brain. According to one of the test subjects, the painless procedure feels like a “small knocking sensation”.

In the past, scientists had used TMS to temporarily improve performance during a test, but this is the first study to show that memory can be improved for at least 24 hours after stimulation.

Not only is the breakthrough useful for improving the memories of healthy humans, it could also help treat people suffering from memory loss following stroke or Alzheimer’s.

"We show for the first time that you can specifically change memory functions of the brain in adults without surgery or drugs, which have not proven effective," Joel Voss, a senior author of the paper, published today in Science, said in a press release. "This non-invasive stimulation improves the ability to learn new things. It has tremendous potential for treating memory disorders."

The research is also the first to show that remembering events requires many brain regions working together with the hippocampus, the key “memory” region of the brain.

Researchers have previously struggled to improve memory using TMS, because the hippocampus is so deep in the brain that the magnetic fields can’t penetrate it. Using an MRI scan, Voss and his team identified a superficial brain region that was just centimetres from the surface of the skull, but that also connected closely to the hippocampus. They decided to see whether stimulating this region could help turn on the hippocampus - and it did.

In fact, the scientists discovered that when TMS stimulated this spot, the regions in the brain involved with the hippocampus became more in sync with each other, and the better these regions worked together, the better people were able to learn new information.

The press release explains that memory, like a symphony orchestra, is made up of different parts of the brain, and the electrical stimulation is like introducing a more talented conductor. “The brain regions played together better after the stimulation,” said Voss.

The study was conducted on 16 healthy adults, who received brain stimulation 20 minutes a day for five consecutive days. They all completed memory tests and had their brain activity monitored and recorded in an MRI scanner before, during and after the TMS. During the experiment, they were also given placebo stimulation. The results showed that after three days of stimulation, test subjects had better memories.

"They remembered more face-word pairings after the stimulation than before, which means their learning ability improved," said Voss. "That didn't happen for the placebo condition or in another control experiment with additional subjects."

The team will now look at how well TMS can help people with early stage memory loss. The procedure could also help people with mental illness, such as schizophrenia, which causes the hippocampus to fall out of sync with the rest of the brain.

"This opens up a whole new area for treatment studies where we will try to see if we can improve function in people who really need it," added Voss.

However, he adds, lot more safety testing and research is required before TMS could be used as a treatment. Find out more in the video below: